Atomic remote memory operations in cache mirroring storage systems

• US 20040168032A1
• Filed: 02/24/2003
• Published: 08/26/2004
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Rao, Raghavendra J., Lee, Whay Sing
• Granted Patent: US 7,020,743 B2
• Time in Patent Office: Days
• US Class Current: 711/141
• CPC Class Codes: G06F 11/1666 where the redundant component is memory or memory area
• CPC Class Codes: G06F 11/20 using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064

Abstract

Embodiments of the present invention provide methods and apparatuses for accessing MD atomically. For one embodiment, the local cache and the remote cache are each provided with an MBE. To perform an atomic access operation, the local processing system allocates a burst descriptor buffer. The burst descriptor buffer is used to specify the addresses to be atomically accessed. For write operations, the burst descriptor buffer also specifies the update data. The addresses, and data, if any, are then transmitted to the remote cache as a series of packets constituting a single data access request. The MBE of the remote cache then performs the operations contained in the request. Upon completion of all of the operations the remote MBE transmits an acknowledgement. For read operations the remote MBE also transmits the requested data.

Claims

1. A data storage system comprising:

a local data storage device including a local cache memory having a local processing device coupled thereto; and

a remote data storage device including a remote cache memory having a remote processing device coupled thereto, the remote processing device coupled via a communications link to the local processing device, such that a plurality of memory access operations transmitted from the local processing device to the remote processing device is performed atomically wherein data stored upon the remote data storage device can not be accessed during performance of the plurality of memory access operations.

2. The data storage system of claim 1 wherein the plurality of memory access operations comprise data modification operations and wherein performing the plurality of data modification operations effects remote data mirroring such that upon completion of the plurality of data modification operations data stored on the remote data storage device is a copy of data stored upon the local data storage device.

3. The data storage device of claim 1 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

4. The data storage device of claim 3 wherein each of the local processing device and the remote processing device are implemented as a network interface chip.

5. The data storage device of claim 1 wherein the plurality of memory access operations comprise data READ operations.

6. A method comprising:

maintaining a first set of data on a local memory device and a second set of data on a remote memory device, the second set of data a mirror copy of the first set of data, the remote memory device having coupled thereto a remote processing device;

updating the first set of data, such that the first set of data is no longer a mirror copy of the second set of data; and

transmitting a memory operation burst containing a set of instructions to perform a plurality of memory update operations to the remote processing device such that the remote processing device performs the plurality of memory update operations atomically wherein the remote memory device can not be accessed while performing the plurality of memory update operations thereby updating the second set of data such that the second set of data becomes a mirror copy of the first set of data.

7. The method of claim 6 wherein each of the local memory device and the remote memory device include cache memory.

8. The method of claim 7 wherein the first set of data and the second set of data comprise metadata.

9. The method of claim 6 wherein the memory operation burst is transmitted to the remote processing device, via a communications link, from a local processing device coupled to the local memory device.

10. The method of claim 9 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

11. The method of claim 10 wherein each of the local processing device and the remote processing device are implemented as a network interface chip.

12. A machine-readable medium having one or more executable instructions stored thereon, which when executed by a digital processing system, cause the digital processing system to perform a method, the method comprising:

maintaining a first set of data on a local memory device and a second set of data on a remote memory device, the second set of data a mirror copy of the first set of data, the remote memory device having coupled thereto a remote processing device;

updating the first set of data, such that the first set of data is no longer a mirror copy of the second set of data; and

transmitting a memory operation burst containing a set of instructions to perform a plurality of memory update operations to the remote processing device such that the remote processing device performs the plurality of memory update operations atomically wherein the remote memory device can not be accessed while performing the plurality of memory update operations thereby updating the second set of data such that the second set of data becomes a mirror copy of the first set of data.

13. The machine-readable medium of claim 12 wherein each of the local memory device and the remote memory device include cache memory.

14. The machine-readable medium of claim 13 wherein the first set of data and the second set of data comprise metadata.

15. The machine-readable medium of claim 12 wherein the memory operation burst is transmitted to the remote processing device from a local processing device coupled to the local memory device via a communications link.

16. The machine-readable medium of claim 15 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

17. The data storage device of claim 16 wherein each of the local processing device and the remote processing device are implemented as a network interface chip.

18. A method comprising:

performing a plurality of data update operations to update a corresponding plurality of data words of a local copy of data stored on a local cache memory, each data word having a corresponding memory address;

transmitting the plurality of updated data words and the corresponding memory addresses as a plurality of packets to a remote processing device coupled to a remote cache memory;

storing each packet at the remote processing device until the plurality of packets is received; and

atomically updating a remote copy of data stored on the remote cache memory using the updated data words and the corresponding memory addresses such that access to the remote copy of data is prevented during updating.

19. The method of claim 18 wherein the local copy of data and the remote copy of data comprise metadata.

20. The method of claim 18 wherein the plurality of packets is transmitted to the remote processing device, via a communications link, from a local processing device coupled to the local cache memory.

21. The method of claim 20 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

22. The method of claim 21 wherein each of the local processing device and the remote processing device are implemented as a network interface chip.

23. The method of claim 20 further comprising:

transmitting an update acknowledgement from the remote processing device to the local processing device upon update completion.

24. A machine-readable medium having one or more executable instructions stored thereon, which when executed by a digital processing system, cause the digital processing system to perform a method, the method comprising:

performing a plurality of data update operations to update a corresponding plurality of data words of a local copy of data stored on a local cache memory, each data word having a corresponding memory address;

transmitting the plurality of updated data words and the corresponding memory addresses as a plurality of packets to a remote processing device coupled to a remote cache memory;

storing each packet at the remote processing device until the plurality of packets is received; and

atomically updating a remote copy of data stored on the remote cache memory using the updated data words and the corresponding memory addresses such that access to the remote copy of data is prevented during updating.

25. The method of claim 24 wherein the local copy of data and the remote copy of data comprise metadata.

26. The method of claim 24 wherein the plurality of packets is transmitted to the remote processing device, via a communications link, from a local processing device coupled to the local cache memory.

27. The method of claim 26 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

28. The method of claim 27 wherein each of the local processing device and the remote processing device are implemented as a network interface chip.

29. The method of claim 26 further comprising:

transmitting an update acknowledgement from the remote processing device to the local processing device upon update completion.

30. A data storage system comprising:

a local data storage device including a local processing unit, a local cache memory, and a local memory burst engine coupled via a communications link to a remote memory burst engine of a remote data storage device, the remote data storage device including a remote cache memory, such that a plurality of memory update operations corresponding to memory updates to the local cache memory are transmitted by the local memory burst engine to the remote memory burst engine, the remote memory burst engine performing the plurality of memory update operations to the remote cache memory atomically such that the remote cache memory can not be accessed during performance of the plurality of memory update operations.

31. The data storage system of claim 30 wherein the local cache memory and the remote cache memory store mirrored copies of metadata.

32. The data storage system of claim 30 wherein the plurality of memory update operations is transmitted to the remote memory burst engine from the local memory burst engine via a communications link.

33. The data storage system of claim 32 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

34. The data storage system of claim 33 wherein each of the local memory burst engine and the remote memory burst engine are implemented as a network interface chip.

35. A method comprising:

transmitting a plurality of memory addresses as a plurality of packets to a remote processing device coupled to a remote cache memory;

storing each packet at the remote processing device until the plurality of packets is received;

atomically reading data from the plurality of addresses on a remote copy of data stored on the remote cache memory such that access to the remote copy of data is prevented during the reading; and

transmitting data words read from the plurality of addresses on the remote copy of data to a local processing device.

36. The method of claim 35 wherein the remote copy of data comprises metadata.

37. The method of claim 35 wherein the plurality of packets is transmitted to the remote processing device, via a communications link, from the local processing device.

38. The method of claim 37 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

39. The method of claim 38 wherein each of the local processing device and the remote processing device are implemented as a network interface chip.

40. A machine-readable medium having one or more executable instructions stored thereon, which when executed by a digital processing system, cause the digital processing system to perform a method, the method comprising:

transmitting a plurality of memory addresses as a plurality of packets to a remote processing device coupled to a remote cache memory;

storing each packet at the remote processing device until the plurality of packets is received;

atomically reading data from the plurality of addresses on a remote copy of data stored on the remote cache memory such that access to the remote copy of data is prevented during the reading; and

transmitting data words read from the plurality of addresses on the remote copy of data to a local processing device.

41. The method of claim 40 wherein the remote copy of data comprises metadata.

42. The method of claim 40 wherein the plurality of packets is transmitted to the remote processing device, via a communications link, from the local processing device.

43. The method of claim 42 wherein the communications link is a network selected from the list consisting of Internet, intranet, wide area network, and local area network.

44. The method of claim 43 wherein each of the local processing device and the remote processing device are implemented as a network interface chip.